Here are some excerpts from Dr. Judith Curry's testimony before Congress.

Dr. Curry is notable because she is much more objective regarding the merits of arguments on both sides of the CAGW equation. She was once more in favor of the CO2 hypothesis, but in the presence of countervailing data - now has a significantly more nuanced view, albeit still somewhat CAGW.

By engaging with decision makers in both the private and public sector on issues related to weather and seasonal climate variability through my company CFAN, my perspective on uncertainty and confidence in context of prediction, and how to convey this, has utterly and irreversibly changed. I have learned about the complexity of different decisions that depend, at least in part, on weather and climate information. I have learned the importance of careful determination and conveyance of the uncertainty associated with a forecast, and the added challenges associated with predicting extreme events. Confidence in a particular probabilistic forecast is determined by consistency of consecutive forecasts, and historical evaluation of forecast accuracy and errors under similar conditions. I have also learned how different types of decision makers make use of forecast uncertainty and confidence information. I have found that the worst forecast outcome is a forecast issued with a high level of confidence that turns out to be wrong; a close second is missing the possibility of an extreme event.


The climate community has worked for more than 20 years to establish a scientific consensus on anthropogenic climate change. The IPCC consensus building process arguably played a useful role in the early synthesis of the scientific knowledge. However, I have argued that the ongoing scientific consensus seeking process has had the unintended consequence of oversimplifying both the problem and its solution, introducing biases into the both the science and related decision making processes. The growing implications of the messy wickedness of the climate change problem are becoming increasingly apparent, highlighting the inadequacies of the ‘consensus to power’ approach for decision making on the complex issues associated with climate change.

The politicization of climate change presents daunting challenges to climate science and scientists. In my assessment, the single most important actions that are needed with regards to climate science – particularly in context of assessments for policymakers – is explicit reflection on uncertainties, ambiguities and areas of ignorance (both known and unknown unknowns) and more openness for dissent. Natural internal variability is a topic of particular importance over which there is considerable disagreement. Disagreement and debate is the soul of the scientific frontier, which is where much of climate science lies.

Greater openness about scientific uncertainties and ignorance, and more transparency about dissent and disagreement, would provide policymakers with a more complete picture of climate science and its limitations. When working with policy makers and communicators, scientists should not fall into the trap of acceding to inappropriate demands for certainty; the intrinsic limitations of the knowledge base need to be properly assessed and presented to decision makers. The role of scientists should not be to develop political will to act by hiding or simplifying the uncertainties, either explicitly or implicitly, behind a negotiated consensus.
There is a lot more - I strongly suggest those interested in climate change to skim through the whole thing.